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Scopolamine – Uses, Dosage, Side Effects, Interactions

Scopolamine is a tropane alkaloid isolated from members of the Solanaceae family of plants, similar to atropine and hyoscyamine, all of which structurally mimic the natural neurotransmitter acetylcholine.^[rx,rx]

Scopolamine Hydrobromide is the hydrobromide salt form of scopolamine, a tropane alkaloid derived from plants of the nightshade family (Solanaceae), specifically Hyoscyamus niger and Atropa belladonna, with anticholinergic, antiemetic and antivertigo properties. Structurally similar to acetylcholine, scopolamine antagonizes acetylcholine activity mediated by muscarinic receptors located on structures innervated by postganglionic cholinergic nerves as well as on smooth muscles that respond to acetylcholine but lack cholinergic innervation. The agent is used to cause mydriasis, cycloplegia, to control the secretion of saliva and gastric acid, to slow gut motility, and prevent vomiting.

Scopolamine is a tropane alkaloid derived from plants of the nightshade family (Solanaceae), specifically Hyoscyamus niger and Atropa belladonna, with anticholinergic, antiemetic and antivertigo properties. Structurally similar to acetylcholine, scopolamine antagonizes acetylcholine activity mediated by muscarinic receptors located on structures innervated by postganglionic cholinergic nerves as well as on smooth muscles that respond to acetylcholine but lack cholinergic innervation. The agent is used to cause mydriasis, cycloplegia, to control the secretion of saliva and gastric acid, to slow gut motility, and prevent vomiting.

Scopolamine is a natural plant alkaloid that has potent anticholinergic effects and is used to treat mild to moderate nausea, motion sickness and allergic rhinitis. Scopolamine has not been implicated in causing liver enzyme elevations or clinically apparent acute liver injury.[rx]

Mechanism of action

Acetylcholine (ACh) is a neurotransmitter that can signal through ligand-gated cation channels (nicotinic receptors) and G-protein-coupled muscarinic receptors (mAChRs). ACh signaling via mAChRs located in the central nervous system (CNS) and periphery can regulate smooth muscle contraction, glandular secretions, heart rate, and various neurological phenomena such as learning and memory.^[rx,rx] mAChRs can be divided into five subtypes, M1-M5, expressed at various levels throughout the brain.^[rx] Also, M2 receptors are found in the heart and M3 receptors in smooth muscles, mediating effects apart from the direct modulation of the parasympathetic nervous system.^[rx] While M1, M3, and M5 mAChRs primarily couple to G_q proteins to activate phospholipase C, M2 and M4 mainly couple to G_i/o proteins to inhibit adenylyl cyclase and modulate cellular ion flow.^[rx] This system, in part, helps to control physiological responses such as nausea and vomiting.^[rx]

Scopolamine acts as a non-selective competitive inhibitor of M1-M5 mAChRs, albeit with weaker M5 inhibition; as such, scopolamine is an anticholinergic with various dose-dependent therapeutic and adverse effects.^[rx,rx] The exact mechanism(s) of action of scopolamine remains poorly understood. Recent evidence suggests that M1 (and possibly M2) mAChR antagonism at interneurons acts through inhibition of downstream neurotransmitter release and subsequent pyramidal neuron activation to mediate neurological responses associated with stress and depression.^[rx] Similar antagonism of M4 and M5 receptors is associated with potential therapeutic benefits in neurological conditions such as schizophrenia and substance abuse disorders.^[rx] The significance of these observations to scopolamine’s current therapeutic indications of preventing nausea and vomiting is unclear but is linked to its anticholinergic effect and ability to alter signalling through the CNS associated with vomiting.^[rx,rx]

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Indications of Scopolamine

Motion sickness
Nausea- vomiting,
Travel sickness or motion sickness
Vertigo, dizziness, Drowsiness
Gastrointestinal tract spasm, Genitourinary spasm
IBS (irritable bowel syndrome)
Postoperative nausea and vomiting
Parkinsonian Tremor
Adjuvants, Anesthesia – Agents that are administered in association with anesthetics to increase effectiveness, improve delivery, or decrease the required dosage.
Cholinergic Antagonists – Drugs that bind to but do not activate CHOLINERGIC RECEPTORS, thereby blocking the actions of ACETYLCHOLINE or cholinergic agonists.
Muscarinic antagonists – Drugs that bind to but do not activate MUSCARINIC RECEPTORS, thereby blocking the actions of endogenous ACETYLCHOLINE or exogenous agonists. have widespread effects including actions on the iris and ciliary muscle of the eye, the heart and blood vessels, secretions of the respiratory tract, GI system, and salivary glands, GI motility, urinary bladder tone, and the central nervous system.
Mydriatics agents – that dilate the pupil. They may be either sympathomimetics or parasympatholytics.
Since little of the medication crosses the blood-brain barrier, this drug has less effect on the brain and therefore causes a reduced occurrence of the centrally-mediated effects (such as delusions, somnolence, and inhibition of motor functions) which reduce the usefulness of some other anticholinergic drugs.
Hyoscine butyl bromide or Scopolamine – is still capable of affecting the chemoreceptor trigger zone, due to the lack of a well-developed blood-brain-barrier in the medulla oblongata, which increases the antiemetic effect it produces via local action on the smooth muscle of the gastrointestinal tract.^[rx]

Contraindications of Scopolamine

Myasthenia gravis, narrow-angle glaucoma, tachycardia, megacolon; hypersensitivity
Hyoscine should not be administered to patients with myasthenia gravis, megacolon, angle-closure glaucoma, tachycardia, prostatic enlargement with urinary retention, gastrointestinal obstruction, mechanical stenosis in the region of the gastrointestinal tract, or paralytic ileus.
Hyoscine should not be given by intramuscular injection to patients being treated with anticoagulant drugs since intramuscular hematoma may occur.
Hypersensitivity to this drug
Allergy
Depression
Porphyria

Dosage of Scopolamine

Strengths: 1.5 mg; 1 mg/mL; 1 mg/72 hr; 0.4 mg/mL; 0.4 mg

Nausea/Vomiting – Post-operative nausea and vomiting (PONV): Apply 1 patch to the hairless area behind the ear the evening before a scheduled surgery.
Motion Sickness – Apply 1 patch to the hairless area behind the ear at least 4 hours before the antiemetic effect is needed

Side Effects Of Scopolamine

The most common

Symptoms of exposure to this chemical include drowsiness, sleepiness, excitement, hallucinations, delirium, psychotic behavior and central nervous system depression.
Other symptoms include narcosis, mydriasis, dryness of the mouth and restlessness.
Drowsiness
Dry mouth
Headache
Indigestion
Depression
Skin rashes
Restlessness
Weight gain
Mydriasis, cycloplegia, eye pruritus.
Muscle weakness.
Urinary retention, dysuria.
Flushing, sweating, dry skin, rash, erythema, pruritus, skin burns, contact dermatitis (transdermal).

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Common

Tachyarrhythmias, hypotension, increased intraocular pressure, drowsiness, confusional states, visual hallucinations, blurred vision, eye pain, idiosyncratic reactions (e.g. agitation, delusion, acute toxic psychosis), epileptic seizures.
Dizziness, headache, equilibrium disturbance, excitement, ataxia, hallucinations, behavioural abnormalities, acute toxic psychosis, agitation, confusion, paranoia, rambling speech, fatigue, migraine, irritability, amnesia, restlessness, sedation.
Bradycardia, Hypersalivation, diarrhea, dry mouth, abdominal cramps, constipation, oesophageal ulceration.
Hyperpyrexia.
Cough producing mucus
difficulty with breathing
tightness in the chest
Abdominal or stomach pain and tenderness
blistering, peeling, or loosening of the skin
Anxiety
dry mouth
irritability
sleepiness or unusual drowsiness
trouble sleeping
Decreased appetite

Serious

Swelling of the hands, arms, feet, ankles, or lower legs
Chest pain
Difficulty breathing
Itching or rash
Dizziness
Lack of energy
Black, tarry, or bloody stools
Bloody vomit, or vomit that looks like coffee grounds
Pale skin
passing out or fainting
seizures

Drug Interactions of Scopolamine

Scopolamine may interact with the following drugs

Due to interactions with the metabolism of other drugs, hyoscine can cause significant unwanted side effects when taken with other medications. Specific attention should be paid to other medications in the same pharmacologic class as hyoscine, also known as anticholinergics. These medications could potentially interact with the metabolism of hyoscine: analgesics/pain medications, ethanol, zolpidem, thiazide diuretics, buprenorphine, anticholinergic drugs such as tiotropium, etc.[rx]

Amitriptyline
Tramadol
Chlorpromazine
Diazepam
Medicines for depression (e.g. tricyclic antidepressants such as amitriptyline)

Pregnancy & Lactation Of Scopolamine

FDA Pregnancy Category C

Pregnancy

The safety of Hyoscine Hydrobromide in human pregnancy has not been established although studies in animals have not demonstrated teratogenic effects. As with other drugs, it is not advisable to administer Hyoscine Hydrobromide in pregnancy.

Lactation

There are no data on the excretion of Hyoscine Hydrobromide in human breast milk. Taking Hyoscine Hydrobromide whilst breastfeeding is not recommended.

What special precautions should I follow?

Before using scopolamine patches,

tell your doctor and pharmacist if you are allergic to scopolamine, other belladonna alkaloids, any other medications, or any of the ingredients in scopolamine patches. Ask your doctor or pharmacist, check the package label, or check the Medication Guide for a list of the ingredients.
tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: antihistamines such as meclizine (Antivert, Bonine, others); medications for anxiety, irritable bowel disease, motion sickness, pain, Parkinson’s disease, seizures or urinary problems; muscle relaxants; sedatives; sleeping pills; tranquilizers; or tricyclic antidepressants such as desipramine (Norpramin), clomipramine (Anafranil), imipramine (Tofranil), and trimipramine (Surmontil) Many other medications may also interact with scopolamine patch, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
tell your doctor if you have angle-closure glaucoma (a condition where the fluid is suddenly blocked and unable to flow out of the eye causing a quick, severe increase in eye pressure which may lead to a loss of vision). Your doctor will probably tell you not to use a scopolamine patch.
tell your doctor if you have or have ever had open-angle glaucoma (increase in internal eye pressure that damages the optic nerve); seizures; psychotic disorders (conditions that cause difficulty telling the difference between things or ideas that are real and things or ideas that are not real); stomach or intestinal obstruction; difficulty urinating; preeclampsia (a condition during pregnancy with increased blood pressure, high protein levels in the urine, or organ problems); or heart, liver, or kidney disease.
tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while using scopolamine patches, call your doctor immediately.
if you are having surgery, including dental surgery, tell the doctor or dentist that you are using scopolamine patches.
you should know that a scopolamine patch may make you drowsy. Do not drive a car or operate machinery until you know how scopolamine patches will affect you. If you participate in water sports, use caution because this medication can have disorienting effects.
talk to your doctor about the safe use of alcoholic beverages while using this medication. Alcohol can make the side effects caused by scopolamine patches worse.
talk to your doctor about the risks and benefits of using scopolamine if you are 65 years of age or older. Older adults should not usually use scopolamine because it is not as safe or effective as other medications that can be used to treat the same condition.[rx]